The invention relates to transmission of electric signals between a control board secured at the center of a steering wheel of a vehicle but in a floating state with respect to the steering wheel and an electric controller fixed on the vehicle.
Among the parts on a vehicle, a steering wheel is located nearest to a driver and within easy access of the driver's hands. Therefore, in order to improve the operability of road-vehicle electric and electronic equipments it is preferable that a control board including key switches used for providing control instructions to the equipments is mounted at the center of the steering wheel in a floating and hence stationary state with respect to the steering wheel.
However, a steering mechanism for transmitting a rotation of the steering wheel to a steering shaft has a complex structure, so it is difficult to make the wiring of signal cables for connecting the control board mounted at the center of the steering wheel (referred to as a steering control board hereinafter) to an electric controller fixed on the vehicle. To facilitate the wiring work, distributing pipes and/or connecting slip rings must be added in the steering mechanism without impairing operation of the mechanism and, in addition, a space allocated for the steering mechanism is limited, so that the wiring is only accomplished with great difficulty.